U.S. patent number 5,472,057 [Application Number 08/387,959] was granted by the patent office on 1995-12-05 for drilling with casing and retrievable bit-motor assembly.
This patent grant is currently assigned to Atlantic Richfield Company. Invention is credited to Michael B. Winfree.
United States Patent |
5,472,057 |
Winfree |
December 5, 1995 |
Drilling with casing and retrievable bit-motor assembly
Abstract
A wellbore is formed in the earth with an elongated,
non-rotating tubular drillstem which may consist of a well casing
or liner and including an expendable sub and reamer bit part
connected to the lower distal end of the drillstem. A retrievable
drilling fluid operated motor and drive member assembly are
disposed in the drillstem. The motor and drive member include
pressure fluid responsive mechanism for engagement with and
disengagement from the reamer bit part to rotatably drive the
reamer bit part and a central bit part connected to the drive
member without rotating the casing type drillstem. The motor, drive
member and central bit part may be retracted from the drillstem
upon completion of drilling operations without retrieving the
expendable reamer bit part.
Inventors: |
Winfree; Michael B. (Anchorage,
AK) |
Assignee: |
Atlantic Richfield Company (Los
Angeles, CA)
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Family
ID: |
25678894 |
Appl.
No.: |
08/387,959 |
Filed: |
February 9, 1995 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
226202 |
Apr 11, 1994 |
|
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Current U.S.
Class: |
175/57; 175/101;
175/107; 175/171; 175/259; 175/267 |
Current CPC
Class: |
E21B
4/02 (20130101); E21B 7/208 (20130101); E21B
10/64 (20130101); E21B 23/04 (20130101) |
Current International
Class: |
E21B
23/04 (20060101); E21B 4/00 (20060101); E21B
7/20 (20060101); E21B 23/00 (20060101); E21B
4/02 (20060101); E21B 10/64 (20060101); E21B
10/00 (20060101); E21B 007/00 () |
Field of
Search: |
;175/57,101,107,171,202,203,259,267,269,278,289 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schoeppel; Roger J.
Attorney, Agent or Firm: Martin; Michael E.
Parent Case Text
This application is a continuation, of application Ser. No.
08/226,202 filed Apr. 11, 1994.
Claims
What is claimed is:
1. A method for drilling a well with a drillstem which is to be
left in the wellbore after drilling has been completed, said method
comprising:
connecting a sub onto the lower end of said drillstem, said sub
having a reamer bit rotatably mounted on the outer surface thereof
whereby said reamer bit remains in the wellbore with said drillstem
when said drilling has been completed, said reamer bit having a
diameter greater than that of said drillstem;
lowering a fluid-operated, downhole motor having a center bit
connected thereto through said drillstem and into said sub wherein
said center bit extends out the lower end of said sub and drivingly
engages said reamer bit for rotation therewith;
circulating a fluid through said drillstem to operate said motor to
thereby rotate both said center bit and said reamer bit to drill a
wellbore having a diameter substantially the same as the diameter
of said reamer bit without rotating said drillstem; and
retrieving said downhole motor and said center bit through said
drillstem while leaving said drillstem and said reamer bit in said
wellbore.
2. Apparatus for drilling a well from the surface onto an earth
formation, said apparatus comprising:
a tubular drillstem extending from the surface and having a central
bore therethrouoh open at its lower end;
a cylindrical reamer bit rotatably mounted on the outer surface of
the lower distal end of said drillstem and having an open central
bore aligned with said central bore of said drillstem, said reamer
bit having an outer diameter greater than that of said drillstem
whereby the diameter of the wellbore of said well to be drilled
with said apparatus shall be greater than that of said
drillstem;
a retrievable, fluid-operated downhole motor insertable into and
retrievable from said drillstem, said motor having a drive shaft
depending therefrom;
a center bit;
means for connecting said center bit to said drive shaft for
rotation and retrieval therewith, said center bit having a diameter
slightly less than that of said central bore of said drillstem
whereby said center bit will extend from said aligned, respective
center bores of said drillstem and said reamer bit when said
retrievable, downhole motor is in its operable position within said
lower end of said drillstem;
releasable means for preventing relative rotational movement
between said downhole motor and said drillstem; and
releasable means for drivingly connecting said center bit to said
reamer bit whereby said reamer bit is rotated upon rotation of said
center bit by said downhole motor.
3. The apparatus set forth in claim 2 wherein:
said reamer bit includes bearing race means disposed thereon for
engagement with rolling element bearings rotatably supporting said
reamer bit on said distal end of said drillstem for transferring
axial and radial forces between said reamer bit and said drillstem
during rotation of said reamer bit.
4. The apparatus set forth in claim 2 wherein said means for
connecting said center bit to said drive shaft comprises:
a drive member having one end connected to said center bit and the
other end connected to said drive shaft;
and wherein said releasable means for drivingly connecting said
center bit to said reamer bit comprises:
at least one drive key mounted for radial movement within said
drive member; and
a piston movably mounted in said drive member and responsive to
fluid acting thereon to move said at least one drive key into
engagement with said reamer bit.
5. The apparatus set forth in claim 4 wherein:
said drive member is drivably connected to a drive shaft of said
motor and includes a bore for receiving pressure fluid from said
motor.
6. The apparatus set forth in claim 5 wherein:
said center bit includes passage means for ejecting pressure fluid
from said drive member to said wellbore for evacuating drilling
cuttings from said wellbore.
7. The apparatus set forth in claim 6 wherein said releasable means
for preventing relative rotation between said downhole motor and
said drillstem comprises:
a latch mechanism including retractable latches carried by said
motor for releasably connecting said motor to said drillstem.
8. The apparatus set forth in claim 7 including:
passage means in said latch mechanism for conducting pressure fluid
from said drillstem to said motor to effect rotation of said drive
member and to provide fluid for evacuating drill cuttings from said
wellbore.
Description
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention pertains to a method and system for drilling
a wellbore with a drillstem or casing which is left in the wellbore
after completion of the drilling using a retrievable motor and bit
assembly and a reamer bit portion on the distal end of the casing
which is rotatably driven by the retrievable bit assembly.
BACKGROUND
In many well drilling operations, it is desirable to minimize the
work required to complete the well by utilizing the so-called
casing or well liner as the drillstem which is left in the wellbore
upon completion of drilling and a separate liner or casing is not
required to be installed upon withdrawal of the drillstem as in
conventional drilling operations.
U.S. Pat. Nos. 5,197,553 and 5,271,472, both by Richard E. Leturno
and both assigned to the assignee of the present invention,
describe one system and method for drilling a well utilizing a
drillstem or tubing which is left in the wellbore to function as a
casing or wellbore liner. The Leturno patents describe, in one
embodiment, a retrievable bit and motor assembly which has
extendable and retractable cutters for drilling a wellbore
sufficiently large in diameter as to accommodate the drillstem or
casing and leave an annular space for circulation of drilling fluid
and further wherein the bit and motor assembly may be retrieved
from the distal end of the drillstem or casing upon completion of
the drilling operation.
However, in drilling certain types of wells, it is desirable to
utilize a type of bit sometimes known as PDC (polycrystalline
diamond compact) or so-called diamond bits which have a bit head in
which certain hard metal or hard mineral inserts are arranged in a
predetermined pattern for cutting or crushing the rock as the bit
is rotated and advanced into the formation material. This type of
bit is often preferred over the so-called roller cone type bits for
certain drilling operations. The diamond type bits lend themselves
to arrangements wherein a portion of the bit may be permanently
mounted to the distal end of the drillstem or casing which is more
desirable than configuring the bit to have extendable and
retractable arms such as in the arrangement described in the
Leturno patents. Moreover, in drilling relatively shallow wells, in
particular, the working life or durability of the PDC type bit,
including the reamer arrangement, is such as to make attractive the
provision of a reamer portion of the bit which is permanently
mounted to the distal end of the drillstem. It is to this end that
the present invention has been developed to provide an improved
method and drilling assembly for drilling wells wherein the
drillstem or casing is to be retained in the wellbore upon
completion of the drilling operation.
SUMMARY OF THE INVENTION
The present invention provides an improved method and apparatus for
drilling a well with a drillstem comprising a "casing" or wellbore
liner which may be left in the wellbore after completion of the
drilling operation.
In accordance with an important aspect of the present invention, a
drillstem comprising a well casing or liner is provided with a bit
portion which is rotatable relative to the drillstem and is
permanently affixed to the distal end thereof and which is
rotatably driven by a downhole drill motor during drilling
operations. Upon completion of drilling operations, the drill motor
may be retrieved without removal of the drillstem or the distal bit
portion.
In accordance with another important aspect of the present
invention, an improved reamer bit portion is provided for use with
well drilling operations wherein the drillstem comprises the well
casing and remains in the wellbore upon completion of the drilling
process. The reamer bit portion is advantageously mounted for
rotation on the distal end of the drillstem on a sub comprising
part of the drillstem and the reamer bit portion includes suitable
drive means for engagement by a drive member of a downhole drill
motor, which drive member includes a retrievable central bit
portion which, together with the reamer bit portion comprises the
hole-forming bit.
In accordance with yet a further aspect of the present invention,
an improved drilling system is provided comprising a well casing, a
casing sub affixed to the distal end of the casing including a
reamer bit portion and a retrievable downhole drill motor and bit
drivingly engaged therewith which is operable to be inserted in the
casing sub and drivingly engaged with the reamer bit portion. The
drill motor is operably connected to the casing so that the drill
motor body is non-rotatable relative to the casing.
In accordance with still a further important aspect of the present
invention, there is provided a unique drill bit assembly comprising
a retrievable bit insertable in the reamer bit and engageable
therewith by releasable lock means which may be pressure fluid
operated by the drilling fluid. The retrievable bit is
advantageously arranged to be drivably connected to the output
shaft of a downhole fluid operated motor. Upon completion of
drilling operations, the motor and central, retrievable bit portion
may be removed from the wellbore so that further wellbore
operations such as cementing of the drillstring or casing in place
may be carried out or further wellbore extending or drilling
operations may be conducted.
Those skilled in the art will further appreciate the above-noted
advantages and superior features of the present invention, together
with other important aspects thereof, upon reading the detailed
description which follows in conjunction with the drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a view in somewhat schematic form of a well being drilled
with the improved drilling apparatus and method of the present
invention; and
FIG. 2 is a longitudinal central section view of the expendable
reamer bit portion and retrievable central bit portion of the
drilling apparatus.
DESCRIPTION OF A PREFERRED EMBODIMENT
In the description which follows, like parts are marked throughout
the specification and drawing with the same reference numerals,
respectively. The drawing figures are not necessarily to scale in
the interest of clarity and conciseness. The subject matter of U.S.
Pat. Nos. 5,197,553 and 5,271,472 is incorporated herein by
reference.
Referring to FIG. 1, there is illustrated a wellbore 10 which is
shown being formed by a unique drilling apparatus, generally
designated by the numeral 12. The drilling apparatus 12 is shown
connected to the distal end of an elongated drillstem 14 which may
comprise a relatively large diameter pipe or so-called well casing,
particularly of the type used in oil and gas wells to reinforce the
wellbore or form a liner therefor. In the illustration of FIG. 1,
the drilling operation is being carried out from a conventional
drill rig 16 which may include a rotary table 18 having a suitable
insert or bushing 20 which may comprise a set of "slips" or
drillstem retaining jaws. In the well drilling method and apparatus
of the present invention, it is contemplated that the drillstem 14
will not normally be rotated during the drilling operation.
Moreover, the drilling operation, although shown being carried out
onshore, may also be carried out as an offshore operation. In the
illustrative example, the well 10 is drilled into an earth
formation 11 and the initial portion of the well 10 is provided
with a suitable supporting pipe or casing section 22 and a drill
fluid receiving and diverting structure 24 of conventional
construction.
During drilling operations, conventional drilling fluid is
conducted to the drillstem 14 from a suitable source by way of a
conduit 26 and cuttings laden drilling fluid is returned to the
surface through the well annulus 13 and the receiver or diverter 24
for flow through a conduit 28 to suitable cuttings separation and
fluid conditioning apparatus, not shown. The aforementioned fluid
is pumped down through the drillstem 14 under substantial pressure
and is ejected at the bottom of the drilling apparatus 12 for flow
upward through the wellbore annulus 13 in a conventional manner to
provide transport of the drill cuttings from the wellbore. In this
regard, the diameter of the wellbore 10 must be such as to provide
a suitable annular space for evacuation of the drill cuttings and
for eventual placement of a suitably thick layer of cement which
will secure the casing 14 in the wellbore to enhance the structural
integrity of the well. The nominal clearance between the drillstem
14 and the wellbore wall may be, for example, on the order of 1.50
to 2.0 inches (38 millimeters-51 millimeters).
In accordance with the invention, the drilling apparatus 12
includes a bit assembly 32 characterized by a generally cylindrical
annular reamer bit portion 34, see FIG. 2, and a retractable
central bit portion 36. The reamer bit 34 is of sufficient diameter
to provide a wellbore diameter, as prescribed above, which is
sufficiently larger than the diameter of the drillstem to provide a
suitable annular space 13 for fluid flow and for cement placement.
The bit assembly 32 is rotatably driven by a downhole fluid
operated motor, generally designated by the numeral 40. The motor
40 is suitably disposed in a generally cylindrical body 42 which is
attached at its upper end to a latch mechanism 44 also having a
generally cylindrical body 46 which supports spaced-apart fluid
seals 48 and suitable latch members 50 which are operable to engage
the drillstem 14 to prevent rotation of the motor body 42. The
motor 40 may be of a type commercially available including a
turbine-type motor or a progressive cavity, positive displacement
type motor which is operated by pressure fluid conducted down
through the drillstem 14 and also comprising the drill cuttings
evacuation fluid. A detailed description of the motor 40 is not
believed to be necessary to enable those skilled in the art to
practice the present invention. One source of a motor of the type
which would be suitable for the drilling apparatus 12 is sold under
the trademark Posi-Drill by Baker-Hughes Incorporated, Houston,
Tex.
Referring further to the drawing figures, the drilling apparatus 12
includes an elongated cylindrical tubular extension member or sub
56 which is adapted to house the drilling motor 40 during drilling
operations. The sub 56 includes at its upper end, a sub part 58
which includes suitable cirumferentially spaced receptacles 60,
FIG. 2, for receiving the latch members 50. The latch mechanism 44
may comprise conventional mechanism known to those of ordinary
skill in the art for extending and retracting the members 50.
Moreover, the latch mechanism 44 may function similar to that
described in U.S. Pat. Nos. 5,197,553 and 5,271,472. As shown in
FIG. 2, the sub part 58 includes suitable threads 62 at its upper
end for connecting the drilling apparatus 12 to the lower end of
the drillstem 14. Still further, as shown in FIG. 1, the upper end
of the latch mechanism 44 may be suitably connected to a fishing
head 66, for example, for insertion and retrieval of the motor 40,
the latch mechanism 44 and the drill bit portion 36, as will be
explained in further detail herein. The insertion and retrievable
operation may be carried out in accordance with the method
described in the aforementioned patents which are incorporated
herein by reference. The latch members 50 may, for example, be
spring biased to latch into the receptacles 60 and under a
sufficient upward pulling force be operable to retract to allow the
latch mechanism 44, motor 40 and bit part 36 to be retrieved from
the sub 56 and the drillstem 14.
Referring further to FIG. 2, the sub 56 has formed at its lower end
suitable bearing race portions 57 and 59. The reamer bit portion 34
includes a generally cylindrical body 35 having a central bore 37,
a plurality of circumferentially spaced latch receptacles 39 and
suitable circumferential bearing race portions 41 and 43, for
example. The bearing race portions 43 and 57 are engageable with
bearing balls 70 to form an angular contact ball bearing assembly,
for example, and the race portions 41 and 59 are engageable with
suitable rollers 72 to form a roller bearing assembly. The
respective bearing assemblies formed by the bearing balls 70 and
the rollers 72 are operable to withstand axial and radial bearing
loads between the sub 56 and the bit part 34. The bit part 34 is
retained on the sub 56 by a suitable split sleeve retainer 74 which
is threadedly engaged with the upper end 76 of the bit part. The
retainer 74 also supports suitable elastomeric seal means 78 to
form a substantially fluid tight seal to prevent incursion of
fluids into the bearings 70 and 72. A second elastomeric seal 80 is
disposed between the latch receptacles 39 and the bearing race 41,
as illustrated.
The bit part 34 includes suitable hard material cutter inserts 82
and so-called gage members 84 arranged in a conventional manner
known to those of skill in the polycrystalline diamond compact bit
art. Accordingly, the reamer bit part 34 is adapted to rotate
relative to the sub 56 and to withstand substantial axial and
radial forces exerted thereon commensurate with the forces incurred
in drilling earth formations with relatively large diameter and
heavy drillstems. Moreover, the simplicity and durability of the
bit part 34 is such as to provide for drilling a wellbore of
substantial depth without requirement to replace this bit part
during drilling operations.
Referring still further to FIG. 2, the drilling apparatus 12 also
includes a reamer bit drive mechanism characterized by a generally
cylindrical body member 90 having separable body parts 92 and 94
which are threadedly engaged with each other at threads 95. The
body part 92 is provided with plural opposed slots 96 for receiving
radially movable drive keys or lugs 98 which are operable to be
engaged with the reamer bit part 34 in the cooperating receptacles
39. The drive keys 98 are operable to be biased in a retracted
position by circular ring spring members 100 not unlike internal
combustion engine piston rings. The body part 94 is provided with a
suitable stepped bore 102, 104 for receiving a piston 106 having a
central bore 108 extending therethrough. The piston 106 is adapted
to support a cylindrical cam 109 engaged with cooperating cam
follower surfaces 110 on the drive keys 98. The cam 109 is retained
on a reduced diameter skirt portion 107 of the piston 106 by
suitable retaining rings 111. The piston 106 is biased into an
upwardly extended position, not shown, by a suitable coil spring
112 retained in an intermediate bore portion 114 of the body part
94. The bit drive member 90 also includes an internally threaded
bore portion 91 at the lower distal end thereof for threaded
engagement with the bit part 36 whereby the bit part may be
replaced if worn or broken. As with the reamer bit part 34, the bit
part 36 includes a suitable arrangement of hard material cutting or
crushing elements 83 and plural passages 85 for ejecting drilling
fluid into the wellbore to entrain and remove drill cuttings from
the wellbore in a conventional manner. As with the reamer bit part
34, the bit part 36 may be constructed substantially in accordance
with known types of rotary PDC type bits having hard metal or
so-called diamond cutter inserts 83, as described above.
The bit drive member 90 is suitably threadedly connected at threads
120 to an output shaft 122 of the motor 40. An internal passage 124
formed in the shaft 122 is in communication with the bore 102, 104
and the passage 108 for conducting pressure fluid to the passages
85. Pressure fluid entering the bore 102 also acts on the piston
106 to bias the piston against the urging of the spring 112 into
the position shown to extend the drive keys 98 into the receptacles
39 so that the drive member 90 is locked for rotation with the
reamer bit part 34. In this way, the bit assembly 32 comprising the
bit parts 34 and 36 rotate together as one member. In response to a
substantial reduction or cessation of flow of pressure fluid
through the bore 102, 104 the piston 106 may retract so that the
cam 109 allows the drive keys 98 to retract radially inwardly clear
of the receptacles 39 whereby the drive member 90, the motor 40 and
the latch mechanism 44 may be withdrawn from the drillstem 14 or at
least moved upward out of the sub 56. The seals 48 may, upon
withdrawal of the latch mechanism 44 upwardly in the drillstem 14,
reach a point where the drilling fluid may flow around these seals
and down through the drillstem to exit the bore 37.
However, in the positions shown in FIGS. 1 and 2, pressure fluid
being conducted down through the drillstem 14 enters a passage 67
in the fishing head 66, if this device is being used, and then
flows through a passage 47 in the latch mechanism 44, see FIG. 2,
then enters the motor 40 and exits the motor through the passage
124 into the bore 102 to urge the piston 106 to the position shown
in FIG. 2. Pressure fluid exiting the motor 40 also flows down
through the bore 108 and the passages 85 to exit the drilling
apparatus 12 and convey drill cuttings upwardly through the annulus
13. With the drive member 90 in the position shown in FIG. 2, the
motor 40 is operable to rotate the bit assembly 32 to affect
cutting of the earth formation and creation of the wellbore 10
without rotating the drillstem 14.
Upon completion of the drilling operation and reduction in the
pressure of the fluid being conducted down through the drillstem,
the motor 40 and the drive member 90, together with the bit part
36, may be removed from the drillstem to provide a substantially
full diameter bore within the drillstem 14 including the sub 56.
The parts for the bit assembly 32 and the drive member 90 may be
constructed of conventional engineering materials used for downhole
motors and drilling mechanisms used in oil and gas well
operations.
The operation of the drilling apparatus 12 is believed to be
understandable to those of ordinary skill in the art from the
foregoing description of the apparatus and the features which
enable it to be inserted and withdrawn from the drillstem 14 while
leaving the drillstem 14 in the wellbore. However, briefly, to
commence drilling with the apparatus 12, the sub 56, in assembly
with the reamer bit part 34, is set in a pair of suitable slips,
not shown, in the rotary table 18. The motor 40 and latch mechanism
44 are then inserted in the sub 56 and the latch mechanism is
operated to latch the motor to the sub part 58. The motor 40 and
the drive member 90 may then be tested for suitable operation by
conducting drilling fluid down through the passage 47, the motor 40
and the drive member 90 to rotate the motor and to lock the drive
keys 98 into the receptacles 39. Once the operation of the motor 40
and bit assembly 32 has been tested, the first section of drillstem
14 may be connected to the upper end of the sub part 58 and
suitably secured thereto, such as by the cooperating threads 62 and
possibly further including welds, not shown, to assure that the
drillstem will not become disconnected from the sub 56. A suitable
circulating head, not shown, is then attached to the upper end of
the drillstem 14, pressure fluid applied through the drillstem and
drilling operations commenced by operating the bit assembly 32 to
rotate the bit parts 34 and 36 locked together and without rotating
the drillstem 14. The drillstem may be lowered by conventional
mechanism such as a hoist and tackle, not shown.
The above-mentioned drilling operation is continued and additional
joints of drillstem are added as needed until the wellbore is
formed to a suitable depth. The last section of drillstem 14 is
preferably fitted with a suitable casing hanger or the like to
suspend the casing from a wellhead structure, not shown, in a
conventional manner.
Upon completion of drilling, a suitable wireline lubricator, such
as described and illustrated in U.S. Pat. Nos 5,197,553 or
5,271,472, is rigged up on top of the last joint of the drillstem
in a conventional manner and a retrieval tool is then lowered
through the drillstem on a suitable line until it engages the
fishing head 66, if used, while the pressure of fluid being
conducted through the drillstring and to the motor 40 is reduced to
allow the piston 106 to retract and drive keys 98 to move out of
engagement with the bit part 34. Once the fishing or retrieval tool
is connected to the latch mechanism 46, motor 40 and drive member
90, an upward pulling effort may be sufficient to effect retraction
of the drive keys 50 out of the receptacles 60 or a suitable
retraction mechanism, not shown, may be activated to retract the
drive keys 50. In fact, the drive keys 50 may be configured to
function in the same manner as the drive keys 98 with suitable
piston and cam means, not shown, responsive to pressure fluid to
bias the keys 50 into their working positions.
After release of the latch mechanism 44 from the sub 56, the motor
40 and drive member 90 may be retrieved from the drillstem 14 and
further operations to secure the drillstem 14 in the wellbore may
proceed in a conventional manner.
Although a preferred embodiment of an apparatus and method in
accordance with the invention have been described in detail
hereinabove, those skilled in the art will recognize that various
substitutions and modifications may be made to the invention
without departing from the scope and spirit of the appended
claims.
* * * * *